Weapons are easily smuggled through so-called naked body scanners, according to new research released Thursday. The devices are no longer used at airports in the United States but remain in other government facilities worldwide.

The Rapiscan Secure 1000 Single Post "backscatter"
scanner - called the “naked scanner” by critics because
of the images it produced of those inside - cannot detect a
weapon hidden on the side of one’s body, according to the team of
researchers from the University of California-San Diego,
University of Michigan, and Johns Hopkins University.

“We performed several trials to test different placement and
attachment strategies. In the end, we achieved excellent results
with two approaches: carefully affixing the pistol to the outside
of the leg just above the knee using tape, and sewing it inside
the pant leg near the same location. … In each case, the pistol
is invisible against the dark background, and the attachment
method leaves no other indication of the weapon’s presence.”

In 2012 a Florida man, Jonathan Corbett, filmed himself
successfully passing through the backscatters with metal at two
different US airports using the same method. At the time, the TSA
responded
to Corbett’s efforts saying the “machines are safe.”

Corbett, who is now suing the TSA over the backscatters, has
encouraged those who did not believe him to “try it.”

The researchers - who presented their findings on Thursday at
Usenix Security Symposium in San Diego - took the challenge,
buying a backscatter on eBay for $49,500.

"What does this say about how these scanners were tested and
acquired in the first place?"
asked one of the study's authors, J. Alex Halderman. "It
says there’s something wrong with the government’s process.”

The report said the explosive C-4 and human flesh appear the same
on a backscatter.

“These scans indicate that plastic explosives can be smuggled
through a Secure 1000 screening, since thin pancakes of these
materials do not contrast strongly with flesh. While a metal
detector would have been sufficient to detect the detonator we
used, not all detonators have significant metal components.”

The backscatters were removed from US airports by June 1, 2013,
according
to the Transportation Security Administration, and replaced with
less invasive body scanners.

Yet backscatters are still used at US prisons and courthouses, as
well as airports in Africa.

New scanners used by the TSA in US airports deploy radio waves to
search for objects and then display the results in a generic
human outline rather than a nude image.

One former TSA employee said earlier this year the federal agency was aware, even
before they were introduced, that the backscatter scanners were
flawed.

“Officers discovered that the machines were good at detecting
just about everything besides cleverly hidden explosives and
guns," said Jason Edward Harrington. "The only thing
more absurd how how poorly the full-body scanners performed was
the incredible amount of time the machines wasted for
everyone.”

The TSA and manufacturer Rapiscan were given advance copies of
the university report. L-3 Communications was the company that
assumed the scanner contract, as it was able to meet the TSA’s
software requirements that called for imaging that did not show a
nude image of travelers passing through security.